There are many practical examples where a piece of information should be marked among a set of information. Such examples include for instance:
In a calendar, one often wishes to mark the exact date. To this end, calendars have been provided wherein figures 1-31 are written on a metal plate and a magnetic material disk can be placed to surround a date to mark it. Similarly, calendars have been provided with means allowing a mark to slide in front of successive figures forming a linear scale.
Various devices have also been devised, wherein sequential figures are arranged on the periphery of a disk, an additional disk or a coaxial pointer acting as a mark opposite one of the figures printed on said periphery.
Various devices incorporating a window have also been devised, which comprise several planes sliding linearly, or disks, for instance of the well-known "parking-disk" type, where an initial time appears through a first window, a second window showing a final time.
In numerous games, such as the game of snakes and ladders, successive squares are provided in such a way that they form various track arrangements on a reference plane. Players push small pieces of plastic or the like (which shall be referred to here as "counters") forwardly on the tracks by following various pre-determined rules, for instance, according to the indications given by dice.
The games of the prior art are suffering from the drawback that the dice or the like roll outside the surface on which they are thrown, and that the dice may be lost, and in any case recovering said dice is drudgery. In order to overcome this drawback, the tracks of the prior art games include flanges which limit the risk of the dice falling from said tracks, yet without eliminating it. But another drawback of such track devices is that their surface is necessarily substantially large, unless the game elements are of an inconveniently small size. Therefore, such devices of the prior art are not particularly suitable to be used as journey games.